Hii, the first thing you can do after clearing JEE Mains is to apply for JEE advanced. The other opportunities are-

• Apply for JOSAA counseling ( centralized counseling top government colleges like NITs and IITs)
• Apply for various state exams such as MHTCET, KCET, KEAM.
• You can also apply for or top most private colleges such as BITS Pilani, MIT(Manipal), VIT(Vellore), SRM Chennai, Thapar Institute of technology (Patiala).
• You can opt for B.Sc with your 12th Board score in top most colleges like Delhi University , Christ college (Bangalore).

I hope this would have helped you. All the best for your future ventures.